1. Field of Invention
This invention relates to bicycles. The invention specifically relates to dual-wheel driven bicycles.
2. Description of Prior Art
U.S. Pat. No. 5,116,070 which issued on May 26, 1992 describes how to create a dual-wheel driven bicycle using an elongated flexible shaft or cable. This cable transfers rotational force from the rear wheel to the front wheel of the bicycle.
The power is derived from driving the rear wheel, like most conventional bicycles, utilizing pedals, a pedal sprocket, a continuous chain, and rear wheel sprocket. A ring gear is attached to the hub of the rear wheel. As the rear wheel rotates, the ring gear rotates. A rear gear assembly is secured rigidly onto the rear of the bicycle frames near the rear ring gear. The rear gear assembly engages the rear ring gear. The rear ring gear drives a gear that is held in the rear gear assembly. The shaft of the rear gear assembly is attached to and rotates an elongated flexible shaft that is directed to the front of the bicycle frame. The shaft runs in a casing or similar guide. The shaft is connected to a front gear assembly. The front gear assembly is rigidly mounted onto the front fork of bicycle near the front wheel hub. A ring gear is attached to the front hub of the front wheel. A gear in the front gear assembly is rotated by the attached flexible shaft. The front gear engages and drives the front ring gear.
The following results when the rear wheel is driven. The rear ring gear rotates to engage the rigidly mounted rear gear assembly. The rear gear assembly rotates to drive the attached elongated flexible shaft. The shaft rotates the front gear assembly. The front gear assembly engages and rotates a front ring gear attached to the front hub of the front wheel. The front wheel is then rotated from the power of the rear wheel to have a constant dual-wheel drive bicycle.
The dual-wheel drive bicycle described in U.S. Pat. No. 5,116,070 requires that a roller clutch or freewheel type device be utilized in the front ring gear or front gear assembly. This is to allow the front wheel to roll independently of the flexible shaft and rear gears. This is needed since the front wheel rolls faster than the rear wheel when the bicycle is turned.
The prior art described in U.S. Pat. No. 5,116,070 may be utilized for single or multi-speed bicycles.
Through use it has been discovered that the prior an of the constant dual-wheel driven bicycle using an elongated flexible shaft, solid shaft, or a combination thereof, creates, additional rotational resistance than conventional single wheel drive bicycles. The resistance is primarily associated with the effort required by the rider to constantly rotate the elongated flexible shaft. In addition, there is constant rotational friction between the flexible shaft, its casing, and resistance associated with the effort to rotate the meshing gear assemblies.
In some riding situations, such as some off road riding and downhill maneuvering, the benefits of the dual-wheel drive system outweighs the rotational resistance problems. In other riding situations, the dual-wheel drive bicycle is more difficult to ride and the dual-wheel drive mode is not needed. The discovery that the constant dual-wheel has resistance problems, combined with the fact that the dual-wheel drive is needed in a limited number of riding situations, has created a need for the present invention. The present invention, the shifting clutch, allows the rider to engage and disengage the dual-wheel drive system at any time while riding or stationary on the bicycle. The shifting clutch allows the dual-wheel drive bicycles to roll as free as a conventional bicycle when dual-wheel drive is not needed. If the riding situation demands, then the dual-wheel drive mode can be used to truly out-perform a single wheel driven bicycle. The shifting clutch improves the prior art of the constant dual-wheel drive bicycle.